Apparatus and methods for providing humidity in respiratory therapy

ABSTRACT

The present inventions provide respiratory therapy apparatus that introduce water into the pressurized air delivered to a user during various positive airway pressure therapies and corresponding methods. The respiratory therapy apparatus may be configured to administer one or more positive airway pressure therapies, including: continuous positive airway pressure therapy (CPAP), bi-level positive airway pressure therapy (BPAP), auto positive airway pressure therapy (autoPAP), proportional positive airway pressure therapy (PPAP), and/or other positive airway pressure therapies. The respiratory therapy apparatus may include a user interface that defines an interface passage to communicate pressurized air to the user for inhalation and a humidifier that introduces water into the pressurized air generally at the interface passage. Methods according to the present inventions may include introducing water into the interface passage at one or more humidifier ports disposed about the interface passage.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. §119(e) of U.S.Provisional Application Ser. No. 60/790,671, filed on Apr. 10, 2006, thedisclosure of which is hereby incorporated by reference in its entirety.A co-pending application filed on Apr. 10, 2007, entitled “APPARATUS ANDMETHODS FOR ADMINISTRATION OF POSITIVE AIRWAY PRESSURE THERAPIES” byBordewick et al. is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Summary of the Invention

The present inventions relate to positive pressurized respiratorytherapy and, more particularly, to humidification apparatus and methodsfor positive pressurize respiratory therapies.

2. Description of the Related Art

Positive airway pressure devices typically deliver pressurized airincluding air and other breathable gasses to a patient by way of thenose in order to prevent upper airway occlusion during sleep. Thepressurized air is typically administered by a mask placed over theuser's nose and/or mouth and at a pressure ranging between about 4 cm to20 cm of water. Positive airway pressure devices have become the devicesof choice for the treatment of chronic sleep apnea, chronic pulmonaryobstruction and snoring. Many variations of positive airway pressuredevices are now commercially available.

A typical positive airway pressure device includes a flow generator, adelivery tube and a mask. In various configurations, the mask may fitover the nose and, sometimes the mouth, may include nasal pieces thatfit under the nose, may include nostril inserts into the flares, or somecombination thereof. The masks frequently include one or more strapsconfigured to secure the mask to the user.

It may be beneficial to provide water in the pressurized air deliveredto the user for therapeutic reasons and also for the comfort of theuser. Accordingly, positive airway pressure apparatus may include ahumidifier. The humidifier is frequently integrated into the flowgenerator. Some humidifiers are configured such that the flow generatorblows pressurized air over a water reservoir in the flow generator. Thepressurized humidified air is then conveyed to the mask through thedelivery tube. Typically, the water reservoir must have a large surfacearea so that a large water reservoir must be provided in the flowgenerator. In addition, the humidified pressurized air may cool as itpasses from the flow generator to the user, which may result incondensation in the delivery tube. Buildup of condensation in thedelivery tube may increase flow resistance and may in the extremeocclude delivery of pressurized air.

Therefore, a need exists for a positive airway pressure device that mayavoid or reduce condensation of water within the delivery tube.

SUMMARY OF THE INVENTION

Apparatus and methods in accordance with the present inventions mayresolve many of the needs and shortcomings discussed above and willprovide additional improvements and advantages that may be recognized bythose skilled in the art upon review of the present disclosure.

Apparatus in accordance with various aspects of the present inventionsmay be configured as a respiratory therapy apparatus. The respiratorytherapy apparatus may include a flow generator that has an outlet. Theflow generator is generally configured to provide pressurized air at theoutlet. The respiratory therapy apparatus may further include a userinterface. The user interface includes a mask and support bands, and theuser interface defines an interface passage. The respiratory therapyapparatus may also include a humidifier configured to introduce waterinto pressurized air passing through the interface passage.

The present inventions include methods for introducing water intopressurized air provided to a user by a respiratory therapy apparatus.The methods may include providing a humidifier, a flow generator, and auser interface with a mask. The user interface defines an interfacepassage that may be in fluid communication with the flow generator. Themethods may include adapting the humidifier to introduce water into theinterface passage.

Other features and advantages of the invention will become apparent fromthe following detailed description and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a perspective view of an exemplary embodiment of apositive airway pressure apparatus in accordance with aspects of thepresent inventions;

FIG. 1B illustrates a perspective view of an exemplary embodiment of auser interface in accordance with aspects of the present inventions;

FIG. 1C illustrates a cross-sectional view of portions of an exemplaryembodiment of a positive airway pressure apparatus in accordance withaspects of the present inventions;

FIG. 1D illustrates a perspective view of an exemplary embodiment ofportions of a user interface in accordance with aspects of the presentinventions;

FIG. 2 illustrates a schematic of an exemplary embodiment of a positiveairway pressure apparatus in accordance with aspects of the presentinventions;

FIG. 3 illustrates another schematic of an exemplary embodiment of apositive airway pressure apparatus in accordance with aspects of thepresent inventions;

FIG. 4A illustrates a side view of an exemplary embodiment of a portionof a user interface in accordance with aspects of the presentinventions;

FIG. 4B illustrates an end view of an exemplary embodiment of a portionof a user interface in accordance with aspects of the presentinventions;

FIG. 4C illustrates an end view of another exemplary embodiment of aportion of a user interface in accordance with aspects of the presentinventions;

FIG. 5A illustrates a side view of an exemplary embodiment of a positiveairway pressure apparatus in accordance with aspects of the presentinventions;

FIG. 5B illustrates a cross sectional side view of another exemplaryembodiment of a portion of a user interface in accordance with aspectsof the present inventions;

FIG. 6A is a schematic diagram of an exemplary embodiment of a controlconfiguration in accordance with aspects of the present inventions;

FIG. 6B illustrates a side view of another exemplary embodiment of aportion of a user interface in accordance with aspects of the presentinventions;

FIG. 6C illustrates a side view of another exemplary embodiment of aportion of a user interface in accordance with aspects of the presentinventions;

FIG. 7A illustrates a cut-away view of an exemplary embodiment of aportion of a humidifier in accordance with aspects of the presentinvention;

FIG. 7B illustrates a cut-away view of a second exemplary embodiment ofa portion of a humidifier in accordance with aspects of the presentinvention; and,

FIG. 7C illustrates a cut-away view of a third exemplary embodiment of aportion of a humidifier in accordance with aspects of the presentinvention; and,

FIG. 7D illustrates a cut-away view of a fourth exemplary embodiment ofa portion of a humidifier in accordance with aspects of the presentinvention.

All Figures are illustrated for ease of explanation of the basicteachings of the present invention only; the extensions of the Figureswith respect to number, position, relationship and dimensions of theparts to form the embodiment will be explained or will be within theskill of the art after the following description has been read andunderstood. Further, the exact dimensions and dimensional proportions toconform. to specific force, weight, strength, flow and similarrequirements will likewise be within the skill of the art after thefollowing description has been read and understood.

Where used in various Figures of the drawings, the same numeralsdesignate the same or similar parts. Furthermore, when the terms “top,”“bottom,” “right,” “left,” “forward,” “rear,” “first,” “second,”“inside,” “outside” and similar terms are used the terms should beunderstood to reference only the structure shown in the drawings andutilized only to facilitate describing the illustrated embodiments.Similarly, when the terms “proximal,” “distal,” and similar positionalterms are used, the terms should be understood to reference thestructures shown in the drawings as they generally correspond withairflow within an apparatus in accordance with the present inventions.

DETAILED DESCRIPTION OF THE INVENTION

The present inventions provide respiratory therapy apparatus 10 andassociated methods for treatment of sleep apnea and other respiratoryand sleeping disorders. The respiratory therapy apparatus 10 aretypically configured to communicate pressurized air to a user lying inbed from a remotely positioned flow generator 20. The respiratorytherapy apparatus 10 may include a flow generator 20, a humidifier 90,and a user interface 40. In certain aspects, the respiratory therapyapparatus 10 may also include a delivery tube 30. The flow generator 20is typically provided as a source of pressurized air. When present, thedelivery tube 30 is configured to communicate pressurized air from theflow generator 20 to the user interface 40. The user interface 40 isconfigured to communicate the pressurized air from the flow generator 20into the airways of a user. Typically, the user interface 40 isconfigured to be secured relative to the user's head such that apositive pressure therapy may be administered to a user as the usersleeps. The humidifier 90 is generally configured to humidify the airdelivered to the user at the user interface 40. In certain aspects, thehumidifier 90 may communicate water into the air at the user interface40. The humidifier 90 may, in some aspects, be generally disposed aboutthe user interface 40.

The Figures generally illustrate exemplary embodiments of respiratorytherapy apparatus 10 in accordance with aspects of the presentinventions. The particularly illustrated embodiments of the respiratorytherapy apparatus 10 have been chosen for ease of explanation andunderstanding of various aspects of the present inventions. Theseillustrated embodiments are not meant to limit the scope of coveragebut, instead, to assist in understanding the context of the languageused in this specification and in the appended claims. Accordingly, theappended claims may encompass variations of the present inventions thatdiffer from the illustrated embodiments.

Respiratory therapy apparatus 10 in accordance with aspects of thepresent invention includes a flow generator 20 configured to provide oneor more positive airway pressure therapies to a user. The one or morepositive airway pressure therapies may include continuous positiveairway pressure therapy (CPAP), bilevel positive airway pressure therapy(BPAP), auto positive airway pressure therapy (autoPAP), proportionalpositive airway pressure therapy (PPRP), and/or other positive airwaypressure therapies as will be recognized by those skilled in the artupon review of this disclosure.

The flow generator 20 typically includes a flow generator housing 22having an outlet 24, with the flow generator 20 adapted to deliverpressurized air to the outlet 24. In order to deliver pressurized air tothe outlet 24, the flow generator 20 may include one or more of variousmotors, fans, pumps, turbines, ducts, inlets, conduits, passages,mufflers, and other components, as will be recognized by those skilledin the art upon review of the present disclosure. A control unit 26 maybe included in the respiratory therapy apparatus 10.

The control unit 26 may be adapted to control one or more components ofthe flow generator 20. The control unit 26 will typically be positionedwithin or on the flow generator housing 22, but may be otherwisepositioned or located, including remotely, as will be recognized bythose skilled in the art upon review of the present disclosure. Thecontrol unit 26 is operably connected to one or more components of theflow generator 20. The control unit 26 may include one or more circuitsand/or may include one or more microprocessors as well as a computerreadable memory.

The control unit 26 is typically configured to output one or morecontrol signals to various components of the flow generator 20 and othercomponents of the respiratory therapy apparatus 10. The control unit 26,in some aspects may be adapted to receive one or more signals from oneor more components of the respiratory therapy apparatus 10. The controlunit 26 may process or otherwise utilize the signals from the componentsof the respiratory therapy apparatus 10 in formulating the one or morecontrol signals output to various components. The control unit 26 may beparticularly adapted to control a humidifier 90, and the control unit 26may be configured to control the humidifier 90 in response toinformation entered through the control interface 28. The control unit26 may be further adapted to control one or more vent valves 84 as wellas other components of the respiratory therapy apparatus 10.

In one aspect, the control unit 26 may control the flow generator 20 inresponse to information including commands from the control interface28. The control interface 28 may include one or more buttons, switches,touch screens, or other controls for controlling the flow generator 20and associated components. The control interface 28 may be incommunication with the control unit 26 to transfer information to andfrom the control unit 26. Portions of the control interface 28 may bemounted on the flow generator housing 22 or may be otherwise positionedon components of the apparatus 10 or remotely as will be recognized bythose skilled in the art upon review of the present disclosure.

The user interface 40 is generally configured to be secured to a userand to communicate pressurized air into the airway of a user. Typically,the user interface 40 will include at least a mask 60, and one or moresupport bands 44 to secure the mask 60 to a user. The user interface 40may define an interface passage 74 that includes at least a chamber ofthe mask 60 such that pressurized air is communicated through theinterface passage 74 for inhalation by the user. The user interface 40may also include a mount 48 and various other features such as pads thatallow the user interface 40 to be affixed to the user and that maintaina proper orientation of the user interface 40 with respect to the user.

The mask 60 may be configured to communicate the pressurized airgenerated by the flow generator 20 to the user's airways. In variousaspects, the mask 60 may be positioned about the user's nose, the user'smouth, or both the user's nose and mouth in order to provide a generallysealed connection to the user for the delivery of pressurized air forinhalation. A pressure greater than atmospheric pressure may be providedwithin the sealed connection. Accordingly, portions of the mask 60 maybe formed of soft silicone rubber or similar material that may provide aseal 76 and that may also be generally comfortable when positionedagainst the user's skin. In various aspects, the mask 60 may includenasal pieces that fit under the user's nose, nostril inserts into theuser's nares, or some combination thereof.

The mask 60 may define an exterior mask surface 62 and an interior masksurface 64. In some aspects, the interior mask surface 64 may define achamber 66. In other aspects, the interior mask surface 64 may define atleast a portion of a chamber 66 when generally sealed about portions ofthe user's face. The mask 60 typically includes one or more mask inlets68 through which pressurized air may be communicated into the chamber66, and one or more seals 76 about which the pressurized air may begenerally communicated to the user. In some aspects, pressurized air maybe inhaled from the chamber 66 by the user. In some aspects, thepressurized air may pass out of the chamber 66 for inhalation by theuser, for example, through one or more apertures 69 surrounded by seals76.

An interface passage 74 is defined by the user interface 40 such thatpressurized air is communicated through the interface passage 74 forinhalation by the user. The interface passage 74 includes the chamber 66from the mask inlet 68 to the seal 76. The interface passage 74 mayfurther include at least the portions, of passageways 138 defined byvarious tubes, conduits, ducts, channels, and other structures that areincluded in the user interface 40 so as to be generally secured aboutthe user's head and through which pressurized air may be communicated tothe mask inlet 68. In some aspects, the interface passage 74 may extendat least distally from a proximal attachment location 134. The proximalattachment location 134 is the most proximal location at which thepassageways 138 defined by various tubes, conduits, channels, and otherstructures included in the user interface 40 may be secured to theuser's head in a generally fixed orientation. In some aspects, supportbands 44 may be provided at the proximal attachment location 134. Invarious other aspects, the proximal attachment location 134 may be atthe mount 48, at some support structure 144, that, in turn, is securedto the mount 48 or to support bands 44, combinations thereof, or othersecurements to the user's head as would be recognized by those skilledin the art upon review of this disclosure. In some aspects, insulationmay be provided about the passageways 138 in order to prevent watercondensation.

In some aspects, the user interface 40 may include the flow generator 20such that the flow generator 20 is generally secured about the user'shead. The flow generator 20 may communicate with the interface passage74 to convey pressurized air to the user for inhalation.

In other aspects, the flow generator 20 is separated from the userinterface 40. A delivery tube 30 may then be secured to an outlet 24 ofthe flow generator 20 to convey pressurized air from the flow generator20 to the user interface 40. In one aspect, the delivery tube 30 may beconfigured as an elongated flexible tube. The delivery tube 30 may becomposed of a lightweight plastic, and often has a ribbed configuration.A delivery tube passage 36 defined by the delivery tube 30 may extendbetween a proximal end 32 and a distal end 34 of the delivery tube 30.The proximal end 32 of the delivery tube 30 may be adapted to be securedto the flow generator 20 with the delivery tube passage 36 in fluidcommunication with the outlet 24 of the flow generator 20. The userinterface 40 may be secured to the distal end 34 of the delivery tube 30in fluid communication with the delivery tube passage 36. Accordingly,pressurized air from the flow generator 20 may be conveyed into thedelivery tube passage 36 of the delivery tube 30 and delivered to theuser interface 40. The distal end 34 of the delivery tube 30 istypically connected to the user interface 40 at a connector 130. In someaspects, the connector 130 may be a rigid structure such as a nipple. Insome aspects, the connector 130 may swivel in order to prevent twistingof the delivery tube 30 by the user during sleep.

In certain aspects, the user interface 40 may include a passageway 138configured as an interface conduit 50. When present, the interfaceconduit 50 may define an interface conduit proximal end 52, an interfaceconduit distal end 54, and a lumen 56. The interface conduit 50 may be,for example, a ribbed plastic hose, a plastic or rubber tube, a pipe, orcombinations thereof. The user interface 40 is configured such that atleast portions of the interface conduit 50 may be generally securedabout the user's head. In aspects of the present inventions that includea delivery tube 30, the distal end 34 of the delivery tube 30 may beconnected to the interface conduit proximal end 52 so that the deliverytube passage 36 is in fluid communication with the lumen 56, which mayallow pressurized air to be delivered from the flow generator 20 to thelumen 56 via the delivery tube passage 36. In aspects of the presentinventions wherein the user interface 40 includes the flow generator 20,the interface conduit proximal end 52 may be adapted to the outlet 24 ofthe flow generator 20 so that pressurized air can be communicated fromthe flow generator 20 into the lumen 56. The interface conduit distalend 54 may be adapted to the mask 60 so that pressurized air may bedelivered from the lumen 56 into the chamber 66 of the mask 60.Accordingly, the interface passage 74 may include at least portions ofthe lumen 56 of the interface tube as well as the mask inlet 68, and thechamber 66 to the seal 76.

One or more vents 80 including holes, louvers, slots and other openingsmay be provided to release pressurized air from the interface passage 74to the ambient atmosphere especially during exhalation by the user togenerally purge exhaled air, which may have a high CO₂ concentration,from at least portions of the interface passage 74. In various aspects,the one or more vents 80 may be included in the mask 60. In aspects thatinclude the interface conduit 50, the one or more vents 80 may beincluded in the interface conduit 50, usually generally proximate to theinterface conduit distal end 54. The one or more vents 80 may includeone or more vent valves 84 positionable between at least a first valveposition 86 and a second valve position 88 to control the release ofpressurized air through the one or more vents 80. In the first valveposition 86, the vent valve 84 may be substantially closed so that airflow through the vent 80 is at a minimum. Airflow through the vent 80may be maximal when the vent valve 84 is in the second valve position88, in which position the vent valve 84 may be substantially open. Incertain aspects, the vent valve 84 may be based in MEMS technology. Invarious aspects, the vent valve 84 may be a butterfly valve, gate, flap,or other as would be recognized by those skilled in the art upon reviewof this disclosure.

The one or more vent valves 84, in some aspects, may be adapted toalternate between at least the first valve position 86 to retain air andthe second valve position 88 to release air including pressurized airand exhaled air in synchronization with the user's breathing cycle. Forexample, the control unit 26 may be adapted to detect the user'sbreathing, and to modulate the one or more vent valves 84 insynchronization with the user's breathing cycle between at least thefirst valve position 86 and the second valve position 88. For example,the one or more vent valves 84 might be positioned in the first valveposition 86 during portions of the inhalation portion of the user'sbreathing cycle and positioned in the second valve position 88 duringportions of the exhalation portion of the user's breathing cycle.

In some aspects, the interface conduit 50 may be adapted to maintain aparticular orientation with respect to the user such as, for example,being generally offset from the face of the user with the mask 60apposed to the user only at the nares. Accordingly, the interfaceconduit 50, in this or other aspects, may include rigid portions havingsufficient rigidity to maintain the particular orientation with respectto the user. The rigid portions of the interface conduit 50 may beconfigured from hard plastics and similar materials or may incorporatevarious wires and other rigid structural elements or combinationsthereof as would be recognized by those skilled in the art upon reviewof this disclosure. Various support structures 144 may also be securedabout the interface conduit 50 in order to maintain the orientation ofthe interface conduit 50. The support structures 144 may also includevarious adjustment mechanisms such that the position of the mask 60 maybe adjusted with respect to the user's nares, nose, and/or mouth, aswould also be recognized by those skilled in the art upon review of thisdisclosure.

Support bands 44 may be attached to portions of the interface conduit50, attached to structures that are, in turn, secured to the interfaceconduit 50, attached to the mask 60, or attached to structures that are,in turn, secured to the mask 60 in order to secure the mask 60 about theuser's head. The support bands 44 are typically in the form of elongatedmembers that are configured to exert sufficient tension to retain theinterface conduit 50 on the head of the user and, more particularly, toretain the mask 60 generally oriented to deliver pressurized air to theuser as the user sleeps. In certain aspects, the support bands 44 areconfigured as flattened straps to comfortably distribute a force overtheir surface area. The support bands 44 may be formed from one or morestretchable elastic materials, substantially unstretchable materials, orother materials as will be recognized by those skilled in the art uponreview of the present disclosure. The support bands 44 may be integrallyformed or interconnected by a variety of mechanical linkages. Thesupport bands 44 may incorporate various buckles, snaps, hook and looptype fasteners, such as that sold under the trade name Velcro®, or othercomponents to link and/or permit relative adjustment of the supportbands 44. Various aspects of the support bands 44 may be adjustable bythe user to position, inter alia, the interface conduit 50 and mask 60.These aspects may include length, relative positions or other aspects aswill be recognized by those skilled in the art upon review of thepresent disclosure.

In some aspects, the mount 48 provides a generally rigid structure towhich portions of the user interface 40 including portions of theinterface conduit 50 and one or more of the support bands 44 may besecured to the mount 48. This may secure portions of the interfaceconduit 50 passing about the mount 48 and extending distally from themount 48 to the user's head. In some aspects, the flow generator 20 maybe at least partly secured to the mount 48 or mounts 48. In someaspects, support structures 144 may be included to secure portions ofthe interface conduit 50 about the user's head and to maintain anorientation of those portions of the interface conduit 50 with respectto the user's head. The support structures 144 may be secured to themount 48.

The humidifier 90 is typically configured to introduce water into thepressurized air passing through the interface passage 74 to humidify thepressurized air. Water includes liquid water, water vapor, andcombinations of liquid water and water vapor. Water in the form of, forexample, water vapor, liquid water droplets, mist, micro-droplets, fog,or various combinations of liquid water and water vapor may beintroduced into the pressurized air passing through the interfacepassage 74 to humidify the pressurized air. The pressurized air may behumidified for therapy, comfort, or other reasons, as will be recognizedby those skilled in the art upon review of the present disclosure. Insome aspects, the water may include pharmacological and othertherapeutic agents so that the humidifier acts as a nebulizer byintroducing the pharmacological and other therapeutic agents into thepressurized air passing through the interface passage 74.

The humidifier 90 includes a water source 92 to store water. In someaspects, the water source 92 may be located in the flow generatorhousing 22. In other aspects, the water source 92 may be separate fromthe flow generator housing 22, and, for example, may be configured intothe user interface 40. The water source 92 is in fluid communicationwith at least one humidifier port 70 situated to introduce water derivedfrom the water source 92 into the pressurized air within the interfacepassage 74 at the humidifier port 70. The humidifier port 70 may beanywhere along the interface passage 74 including in the interfaceconduit 50 or in the mask 60 or combinations thereof. The humidifierport 70 is configured accordingly to allow the introduction of waterinto the interface passage 74. In some aspects, there may be a pluralityof humidifier ports 70 to introduce water at various points along theinterface passage 74. The water source 92 may be a reservoir or othersource of water. In certain aspects, the water source 92 may be securedto the user interface 40. In some aspects, the water source 92 mayinclude baffles, absorbent materials, or other features to preventsloshing. The water source 92 may be in fluid communication with thehumidifier port 70 by a water tube 98 such that fluid may be conveyedfrom the water source 92 to the humidifier port 70.

Water flow through various components including the water tube 98 may begravity driven, at least in part, in some aspects. In various aspects, apump 96, including a micro-pump and other devices that transfer energyinto a fluid, may be used to convey water from the water source 92 tothe humidifier port 70 through the water tube 98 or through otherportions of the apparatus 10. Capillary effects may also be used toconvey water from the water source 92 through the water tube 98. A pump96 or series of pumps 96 may also be provided to introduce the waterinto the pressurized air passing along the interface passage 74 at thehumidifier port 70. One or more flow valves 168 may be positioned toregulate the flow of water within the humidifier 90 including theintroduction of water into the interface passage 74 at the humidifierport 70. The flow valve 168 may be configured as a needle valve,butterfly valve, globe valve, or other valve. The water may beintroduced as, for example, a spray or a vapor, or combinations thereof.Accordingly, various nozzles 106 including sprayers, orifices, jets,vaporizers, and heaters 154, and similar devices and combinationsthereof may be provided to introduce the water at the humidifier port70. In various aspects, the nozzles 106, heaters 154, and similardevices and combinations thereof may be located generally proximate thehumidifier port 70. Transducers 158 including ultrasonic, piezo-ceramic,and other transducers may be employed in some aspects, for example, togenerate water vapor, micro-droplets, mist, or combinations thereof.

Various aspects may include one or more capillary pumps 94. The one ormore capillary pumps 94 may be configured to use heat to convert watergenerally in the liquid phase to water generally in the vapor phase insome aspects. In various aspects, the capillary pumps 94 may beconfigured to generate water generally in the form of a mist or in theform of micro-droplets. Heaters 154 may be employed in the humidifier 90in various ways to facilitate conversion of water generally in theliquid phase to water generally in the vapor phase as would beunderstood by those skilled in the art upon review of this disclosure.Heaters 154 may be provided at various locations in the humidifier 90.The water generally in the vapor phase may then be introduced into theinterface passage 74 at the one or more humidifier ports 70.

In some aspects, an exchange material 110 may be provided in theinterface passage 74 at the humidifier port 70. The exchange material110 may be configured as a mesh, screen, porous material, molecularsieve, or other material that may, for example, attract water bycapillary action or may have various surface properties to transportwater over the surface. In some aspects, the exchange material 110 maybe configured to allow pressurized air to flow through. Water may thenbe conveyed from the water source 92 through one or more water tubes 98to the exchange material 110. The exchange material 110 may then collectthe water from the one or more water tubes 98, and the water may beintroduced into the pressurized air by evaporation as the pressurizedair passes about the exchange material 110. In various aspects theexchange material 110 may occupy various portions of the interfacepassage 74 and the water may be distributed over the exchange material110 at a plurality of locations. In some aspects, various additives maybe included in the water, for example, in order to enhance the capillaryaction of the exchange material 110 or to enhance evaporation. Heat maybe provided to the exchange material 110 and/or to the water in order toenhance evaporation in some aspects.

In some aspects, the humidifier port 70 may be distal of the vent 80,while in other aspects the humidifier port 70 may be proximal of thevent 80. In various aspects, the introduction of water may be periodic.For example, the introduction of water may be synchronized with at leastphases of the user's breathing cycle. The phases of the user's breathingcycle may include at least an inhalation phase and an exhalation phase.For example, water may be introduced into the pressurized air at thehumidifier port 70 generally during the inhalation phase of thebreathing cycle, so that the water is generally delivered to the user.No water is introduced generally during the exhalation portion of thebreathing cycle in order to prevent water release through the vents 80to the ambient atmosphere. Synchronization may provide greaterhumidification efficiencies by humidification of the inspired air whileminimizing wasted humidification of expired air. In various aspects, ameasured amount of water may be introduced into the pressurized air atthe humidifier port 70 to control the humidity delivered to the user.For example, a measured volume of water could be introduced into thepressurized air at the humidifier port 70 generally during theinhalation phase of the breathing cycle.

In some aspects, the water introduction may be synchronized with thepositioning of the vent valves 84 and may also be synchronized with theuser's breathing cycle. For example, water may be introduced into thepressurized air at the humidifier port 70 when the one or more ventvalves 84 are positioned in the first valve position 86 so that thewater is retained for delivery to the user. No water is introduced whenthe vent valves 84 are positioned in the second valve position 88because the water might be released through the open vents 80 to theambient atmosphere. In various aspects, the control unit 26 may beoperably connected to the one or more vent valves and may be configuredto control the introduction of water into the interface passage 74. Thecontrol unit 26 may be configured to detect phases of the user'sbreathing cycle, to control the introduction of water into the interfacepassage 74, and to control the position of the vent valves 84 in waysthat would be readily recognized by those skilled in the art upon reviewof this disclosure. In some aspects having a plurality of vent valves84, the valves may be positioned in harmony, so that, for example, everyvent valve 84 is positioned in the first valve position 84. In otheraspects having a plurality of vent valves, the valve may bedisharmoniously positioned, so that, for example, some of the ventvalves 84 may be positioned in the first valve position 84 while othervent valves 84 in the plurality of vent valves 84 may be positioned inthe second valve position 86. In various aspects, one or more ventvalves may be positionable in positions other than the first valveposition 84 and the second valve position 86.

Some aspects of the respiratory therapy apparatus 10 may include a heatand moisture exchanger in addition to the humidifier 90, which mayreduce the amount of water that the humidifier 90 introduces in order tomeet patient needs. The heat and moisture exchanger typically includeshygroscopically treated material [HME material] to collect heat andwater from expired air to warm and humidify the gas subsequentlyinspired by the user. In some embodiments, the HME material may bepositioned distal from the vent 80 to prevent loss of water through thevent 80. For example, the HME material may be placed in a portion of thechamber 66 defined by the mask 60.

In operation, the user interface 40 may be secured to the user's headand the mask 60 positioned with respect to the user's nose and/or mouth.In some aspects, the delivery tube 30 may be secured to the userinterface 40 and to the outlet 24 of the flow generator 20. Therespiratory therapy apparatus 10 may then be activated. The respiratorytherapy apparatus 10 delivers humidified pressurized air to the user inorder to provide a respiratory therapy.

FIG. 1 A generally illustrates a respiratory therapy apparatus 10according to the present inventions. As illustrated, the respiratorytherapy apparatus 10 includes a flow generator 20, a delivery tube 30,and a user interface 40. The flow generator 20, in this embodiment, hasa control interface 28 configured into the flow generator housing 22.Also, in this embodiment, the flow generator 20 includes portions of thehumidifier 90.

The proximal end 32 of the delivery tube 30 is attached to the outlet 24of the flow generator 20, as illustrated in FIG. 1A. In this embodiment,water may be conveyed from the water source 92 in the flow generator 20and introduced into the pressurized air passing through the interfacepassage 74 at the humidifier port 70 through a water tube 98, which maybe located within the delivery tube 30. A cross-section of the deliverytube 30 is illustrated in FIG. 1C, which shows the water tube 98 withinthe delivery tube passage 36. The water tube 98, in this embodiment, isadapted to convey water from the water source 92 to a humidifier port 70in the interface passage 74 at the user interface 40. The water is thenintroduced into the interface passage 74 through a nozzle 106, as shownin FIG. 1D. In other embodiments, the water tube 98 may be external tothe delivery tube 30, and may be secured to the delivery tube 30 by, forexample, various snaps, clips, and pre-molded hooks or clips.

A passageway 138 within the user interface 40 is defined by an interfaceconduit 50, in this embodiment. The distal end 34 of the delivery tube30 is attached to the interface conduit proximal end 52 in theillustration at a connector 130. The interface conduit 50 is secured tosupport structures 144 which are, in turn, secured to the mount 48 toform a portion of the user interface 40. The portion of the interfaceconduit 50 distal of the proximal attachment location 134 is generallysecured to the head of the user and may be generally secured in aparticular orientation with respect to the head of the user. Asillustrated, the interface conduit 50 is cantilevered from the mount 48and angled so that the mask 60 may be sealed about the user's nareswithout the interface conduit 50 touching the user's face. The userinterface 40 includes support bands 44 that may be used to secure theuser interface 40 about the user's head. In FIG. 1A, the interfaceconduit distal end 54 is illustrated as attached to the mask 60. Themask 60 is configured to be sealed about the user's nares and togenerally touch the user's face generally proximate the nares.

FIG. 1B illustrates a perspective view of portions of the respiratorytherapy apparatus 10 including the user interface 40 secured about theuser's head. Aspects of the humidifier 90 including the water source 92are also illustrated in FIG. 1B. A passageway 138 within the userinterface 40 is defined by an interface conduit 50, in this embodiment.In this Figure, the interface conduit 50 extends proximal to the user,and the interface conduit proximal end 52 is attached to the distal end34 of the delivery tube 30 by a connector 130. The interface conduitdistal end 54 is joined to the mask 60. The mask 60 is configured toseal about the user's nares at the seals 76, as illustrated. Theinterface conduit 50 is generally held in a specific orientation by thesupport structure 144 distal of the proximal attachment location 134.The proximal attachment location 134, as illustrated, is near the mountproximal end 47 where the interface conduit 50 is secured to the mount48. The interface conduit 50 is cantilevered from the mount 48 in such away that the interface conduit 50 is securely held generally away fromthe user's face. Only portions of the mask 60 contact the user's facegenerally about the nares in this embodiment. Accordingly, at leastportions of the interface conduit 50 extending distal of the proximalattachment location 134 are integral with the user interface 40 anddefine a portion of the interface passage 74. Vents 80 are also providedin the interface conduit 50 generally toward the interface conduitdistal end 54 that may generally purge exhaled air. Support bands 44 areattached to the mount 48 to secure the user interface 40 about theuser's head. In this embodiment, the water source 92 is attached to themount 48 to provide a source of water for the humidifier 90. Theinterface passage 74, as delineated in this Figure, may start at theinterface conduit proximal end 52 to include the lumen 56 of theinterface conduit 50 and the chamber 66 of the mask 60, and terminatingat the intersection of the mask 60 with the user's nares.

Portions of the humidifier 90 including the water source 92 are securedto the mount 48 in the embodiment of FIG. 1B. In this embodiment, watermay then be conveyed from the water source 92 through the water tube 98to the humidifier port 70. In this particular embodiment, the humidifierport 70 is proximal to the proximal attachment location 134 and thehumidifier port 70 is proximal to the vents 80. Water may be introducedinto pressurized air passing along the interface passage 74 at thehumidifier port 70. In other embodiments, the humidifier port may bedistal to the proximal attachment location 134, within the mask 60, oranywhere along the interface conduit 50.

FIG. 2 illustrates an embodiment of portions of the respiratory therapyapparatus 10 including the humidifier 90. In this embodiment, thepassageway 138 is defined by a portion of the user interface 40 securedto the mask 60. The portion of the user interface 40 that defines thepassageway 138 in this embodiment may be generally configured to besecured to the user's head, so that the passageway 138 is generally in afixed orientation with respect to the user's head. The mask 60, asillustrated, is configured to seal about the user's nares in order todeliver pressurized air to the user for inhalation. Pressurized airpasses along the interface passage 74 including the passageway 138defined by the portion of the user interface 40, through the mask inlet68, into the chamber 66, and exits through apertures 69 surrounded byseals 76 into the user's nares. The arrows in this and subsequentfigures may be generally indicative of the flow of pressurized air orthe flow of water. Vents 80 for the release of excess pressurized airare located in the passageway 138 generally near the mask 60 in thisembodiment. The vents 80, in this embodiment, are configured as a seriesof holes about the circumference of the interface conduit 50. A portionof the interface passage 74 generally near the interface conduit distalend 54 and the chamber 66 is also illustrated.

As illustrated in FIG. 2, water may be delivered from the water source92 to a capillary pump 94 by a water tube 98. The water source 92 may bepositioned at any convenient location about the respiratory therapyapparatus 10. In this illustrated embodiment, one or more pumps 96 areprovided to pump the water in liquid phase from the water source 92through the water tube 98 to the capillary pump 94. The capillary pump94, as illustrated, introduces the water into pressurized air passingthrough the lumen 56 of the interface conduit 50 at the introductionpoint generally as a vapor with the introduction point configuredaccordingly. The water may then be conveyed along the interface passage74 through the remainder of the interface conduit 50, through the mask60, and into the user's nares at the points of inhalation along withpressurized air conveyed from the flow generator 20. In this embodiment,the introduction point is distal of the vents 80 so that waterintroduced at the introduction point may be more likely to pass into theuser's nares and less likely to escape through the vents 80.

FIG. 3 illustrates another embodiment of portions of the respiratorytherapy apparatus 10 including the humidifier 90. In this embodiment,the distal end 34 of the delivery tube 30 is secured to the mask 60 at aconnector 130 that generally fowls the mask inlet 68. The connector, inthis embodiment, may allow the delivery tube to swivel in order to avoidkinks and twists in the delivery tube while allowing the user interface40 including the mask 60 to maintain a generally fixed orientation withrespect to the user. The mask 60, as illustrated, is configured to besecured about the user's nose and mouth so that the user may breathepressurized air either through the nose or through the mouth. The mask60 includes the seal 76 around the periphery of the mask 60 to contactthe user's face. Support bands 44 are attached to the mask 60 in thisembodiment to generally sealably secure the mask 60 to the user's face.In this embodiment, the mask 60 includes vents 80 configured as a seriesof holes, which are disposed about the mask 60 for the release ofpressurized air during exhalation by the user. Pressurized air passesalong delivery tube passage 36 and into the user interface 40 at theproximal end of the connector 130, through the mask inlet 68, and intothe chamber 66 where the pressurized air may be breathed by the user.The chamber 66, in this embodiment, is defined in part by the interiorsurface of the mask 60 and, in part, by the user's face when the mask 60is sealably secured to the user's face. The interface passage 74 mayextend from the mask inlet 68 through the chamber 66 in this embodiment.

As illustrated in FIG. 3, water may be conveyed from the water source 92through water tubes 98 to capillary pump 94 by pump 96. The capillarypump 94 in this embodiment is positioned proximate the humidifier port70 on the mask 60. The capillary pump 94 introduces water into theinterface passage 74 where the water may mix with the pressurized airand be inhaled by the user. The second humidifier port 70, in thisembodiment, includes the transducer 158 that may convert liquid waterinto microdroplets and/or water vapor, which may then be introduced intothe interface passage 74.

FIGS. 4A, 4B, and 4C illustrate a portion of the passageway 138 definedby an interface conduit incorporated into the user interface. Theillustrated portion of the interface conduit 50 includes an exchangematerial 110 generally disposed about the humidifier port 70. In thisembodiment, the humidifier 90 introduces water from the water source 92onto the exchange material 110. The exchange material 110 is positionedin the lumen 56 of the interface conduit 50 and configured such thatpressurized air may pass through the exchange material 110 along theinterface passage 74 to evaporate the water from the exchange material110 as illustrated in the cross-section of FIG. 4B. In an alternativeembodiment, the exchange material 110 may be placed circumferentiallyabout the lumen 56, as illustrated in FIG. 4C. Water may be introducedfrom the exchange material 110 into the pressurized air generally byevaporation, as illustrated. In these embodiments, several water tubes98 are disposed generally about the circumference of the interfaceconduit 50 at the humidifier port 70 to introduce water onto theexchange material 110. The exchange material 110 may collect the waterby capillary action. In various embodiments, water tubes 98 may bedistributed generally longitudinally along the interface conduit 50 aswell as circumferentially.

The embodiment illustrated in FIGS. 5A and 5B includes a flow generator20 that is attached to the user interface 40 generally about the mount48. A plurality of support bands 44 are provided to secure the userinterface 40 including the flow generator 20 about the user's head. Apassageway 138 extending from the flow generator housing 22 to the mask60 is defined by the interface conduit 50 and is maintained in agenerally fixed orientation with respect to the user's head in thisillustrated embodiment. The interface conduit 50 is shown as extendingfrom the flow generator housing 22 and bending to pass over the user'sface without touching the user's face and is generally in a fixedorientation with respect to the user's head including the face. Theinterface conduit distal end 54 is secured to the mask 60, asillustrated. The interface passage, in this embodiment, includes thepassageway 138, the mask inlet 68, and the chamber 66 of the mask 60.Vents 80 are included along the interface passage 74 in the interfaceconduit 50, as illustrated. The mask 60, in this embodiment, may besealed about the user's nares to deliver pressurized air for breathingby the user.

In the embodiment illustrated in FIGS. 5A and 5B, portions of thehumidifier 90 are located within the flow generator housing 22. Theseportions of the humidifier 90 may include the water source 92 and one ormore pumps 96 to convey water. The passageway 138 is configured as aninterface conduit 50 in this embodiment. The water tube 98 extendsdistally from the flow generator 20 within the lumen 56 defined by theinterface conduit 50 to introduce the water into the interface passage74. The water tube distal end 104, as illustrated, is located distal ofthe vents 80 within the lumen 56. In this embodiment, water may beintroduced into the water tube 98 within the flow generator housing 22,conveyed by the water tube 98 through portions of the lumen 56, andintroduced out of the water tube distal end 104 into pressurized airpassing though the lumen 56 to humidify the pressurized air. The watertube distal end 104 defines the humidifier port 70 and may be configuredas a nozzle 106 to introduce the water by spraying, as illustrated, orin various other ways as would be understood by those skilled in the artupon review of this disclosure. The humidified pressurized air may thenpass through the mask 60 and into the user's airways. In variousembodiments, the water tube 98 may be configured to introduce water intothe interface passage 74 at any location along the interface passage 74.

FIGS. 6A, 6B, and 6C illustrate the control unit 26 in communicationwith vent valves 84 positioned at vents 80, with the pump 96 proximatethe humidifier port 70, with the humidifier 90 generally, with the flowgenerator 20, and with the control interface 28. Communication may be bywire, may be wireless such as by Bluetooth® or other wireless protocols,or combinations thereof. In this embodiment, the humidifier port 70 isin the interface conduit 50 distal of the vents 80. As illustrated, thecontrol unit 26 detects at least inhalation and exhalation in order tosynchronize valve closures and the introduction of water pulses by thepump 96 with inhalations and valve opening with exhalations. In otherembodiments, the control unit 26 may detect other features of thebreathing cycle and synchronize the valves 84 to various portions of thebreathing cycle. The control unit 26 may accept inputs from the userinterface 28 and may also control the flow generator 20 and control thehumidifier 90 generally in various ways that would be recognized bythose of skill in the art upon review of this disclosure.

During inhalation, the pressurized air passes generally in the directionof the interface conduit distal end 54, as illustrated in FIG. 6B. Thevent valves 84, as illustrated, are placed in the first valve position86 during inhalation and a pulse of water in the form of a jet from thenozzle 106 is introduced into the pressurized air passing along theinterface passage 74 by the pump 96 as directed by the control unit 26.The pulse of water humidifies the pressurized air. The humidifiedpressurized air may then pass along the interface passage 74 forinhalation by the user.

During exhalation, as illustrated in FIG. 6C, at least a portion of theair exhaled by the user may pass into the lumen 56 of the interfaceconduit 50. The control unit 26 positions the vent valves 84 in thesecond valve position 88 during exhalation so that the exhaled air alongwith pressurized air may then exit through the vents 80. No water isintroduced during exhalation, as such water may be conveyed out thevents 80 into the ambient atmosphere.

FIGS. 7A, 7B, 7C, and 7D illustrate embodiments of portions of thehumidifier 90. The embodiment illustrated in FIG. 7A illustrates thepump 96 configured to introduce water into the interface passage 74through humidifier port 70 that includes the nozzle 106. In theembodiment illustrated in FIG. 7B, the water may be heated by the heater154 prior to introduction into the interface passage 74. The humidifierport 70 includes a plurality of nozzles 106 configured as orifices inthis embodiment. The embodiment illustrated in FIG. 7C includes thetransducer 158. Water passes through the transducer 158 and isintroduced through the humidifier port 70. Water flow through the watertube 98 may be gravity driven in the embodiment illustrated in FIG. 7D.In this embodiment, the introduction of water into the interface passagethrough nozzle 106 may be regulated by flow valve 168.

The present inventions also provide methods for introducing water intothe pressurized air provided by the respiratory therapy apparatus 10.The methods include providing a respiratory therapy apparatus 10including a flow generator 20 for generating pressurized air and a userinterface 40 including a mask 60 for delivering the pressurized air tothe user for inhalation. The mask 60 defines at least a portion of achamber 66. The mask 60 includes a mask inlet 68 and a seal 76. Themethods may include communicating pressurized air through the interfacepassage 74 defined by the user interface 40 for inhalation by the user.The interface passage 74 includes the chamber 66. The interface passage74 may further include at least the portions of passageways 138 definedby various tubes, conduits, ducts, channels, and other structures thatare included in the user interface 40 so as to be generally securedabout the user's head and through which pressurized air may becommunicated to the mask inlet 68. The methods may include providing ahumidifier 90, and configuring the humidifier 90 to introduce water intopressurized air passing along the interface passage 74. The methods mayfurther include introducing water into the interface passage 74.

Some methods may also include providing a delivery tube 30 for conveyingpressurized air from the flow generator 20 to the interface passage 74defined by the user interface 40. In some aspects, water may beintroduced at multiple humidifier ports 70 along the interface passage74. In some aspects, the methods may include providing a water source92. In certain aspects, the methods may include providing one or morepumps 96 to deliver the water from the water source 92 to the humidifierport 70. In certain aspects, the methods may include providing one ormore capillary pumps 94. Various aspects may include providing one ormore pumps 96 to introduce water into the interface passage 74. Variousaspects may include providing one or more transducers 158 to introducewater into the interface passage 74. Various aspects may includeproviding one or more heaters 154 for use in the introduction of waterinto the interface passage 74. Various aspects may include providing oneor more flow valves 168 for regulating the introduction of water intothe interface passage 74. Various aspects may include providing one ormore capillary pumps 94 for introducing water into the interface passage74. in some aspects, the methods may include providing an exchangematerial 110, the exchange material 110 generally disposed in theinterface passage 74, applying the water to the exchange material 110,and evaporating and/or otherwise introducing the water from the exchangematerial 110 into the pressurized air passing through the interfacepassage 74. In some aspects, the methods may include providing a nozzle106 and introducing the water into the pressurized air passing throughthe interface passage 74 through the nozzle 106. In various aspects, themethods may include introducing the water into the pressurized airpassing through the interface passage 74 generally in vapor phase,generally in liquid phase, or generally in combinations of liquid andvapor phases.

Certain aspects may involve providing one or more vents in the interfacepassage 74 and introducing the water distal of the one or more vents 80,proximal of the one or more vents 80, or both distal and proximal of theone or more vents 80. Some aspects may further include providing one ormore vent valves 84 and may also include controlling the one or morevent valves 84 by the control unit 26 to alter the one or more ventvalves 84 between a first valve position 86 and a second valve position88. The control unit 26 may be configured to detect user inhalation anduser exhalation and to alter the one or more vent valves 84 between thefirst valve position 86 and the second valve position 88 generally insynchronization with user inhalation and user exhalation. The controlunit 26 may be configured to introduce water into the interface passage74 during user inhalation.

The foregoing discussion discloses and describes merely exemplaryembodiments of the present inventions. Upon review of the specification,one skilled in the art will readily recognize from such discussion, andfrom the accompanying figures and claims, that various changes,modifications and variations can be made therein without departing fromthe spirit and scope of the invention as defined in the followingclaims.

1-34. (canceled)
 35. An apparatus for providing positive pressurerespiratory therapy to a user, the apparatus comprising: a flowgenerator configured to deliver pressurized air at an outlet; a userinterface defining an interface passage in fluid communication with theoutlet of the flow generator, the interface passage defining at leastone vent, wherein the user interface also comprises a mask defining achamber of the interface passage, the mask configured to attach to theuser such that the chamber is in fluid communication with an airway ofthe user, wherein the pressurized air provided by the flow generator isdelivered through the interface passage into the chamber of the mask forinhalation by the user; and a humidifier configured to introduce waterinto the interface passage at a location distal of both the flowgenerator and the at least one vent.
 36. The apparatus of claim 35,wherein the humidifier is configured to introduce the water into thepressurized air passing through the interface passage.
 37. The apparatusof claim 35, wherein the water comprises one or more of water vapor,liquid water droplets, mist, microdroplets, fog, and combinations ofliquid water and water vapor.
 38. The apparatus of claim 35, wherein thechamber defines a distal portion of the interface passage, and whereinthe humidifier is configured to introduce the water into the chamber.39. The apparatus of claim 35, wherein the humidifier is configured tointroduce the water into the interface passage via a plurality ofhumidifier ports.
 40. The apparatus of claim 35, further comprising aninterface conduit positioned between the outlet of the flow generatorand a mask inlet, the interface conduit forming a portion of theinterface passage, wherein the at least one vent is formed in theinterface conduit near the mask inlet.
 41. An apparatus for providingpositive pressure respiratory therapy to a user, the apparatuscomprising: a flow generator configured to deliver pressurized air at anoutlet; a user interface defining an interface passage in fluidcommunication with the outlet of the flow generator, the interfacepassage defining a vent, wherein the user interface also comprises amask defining a chamber of the interface passage, the mask configured toattach to the user such that one or more seals of the mask provides asealed connection to an airway of the user, wherein the pressurized airprovided by the flow generator is delivered through the interfacepassage into the chamber of the mask; and a humidifier configured tointroduce water into the interface passage at a humidifier port that islocated between the vent and the one or more seals.
 42. The apparatus ofclaim 41, wherein the humidifier comprises a water source connected tothe humidifier port by a water tube.
 43. The apparatus of claim 42,wherein the interface passage is connected to a delivery tube, the watertube positioned within a lumen formed by the delivery tube.
 44. Theapparatus of claim 42, wherein the interface passage is connected to adelivery tube, the water tube positioned external to the delivery tube.45. The apparatus of claim 42, further comprising one or more pumpsconnected to the water tube to convey the water through the water tube.46. The apparatus of claim 45, wherein the one or more pumps is acapillary pump configured to use heat to convert at least some of thewater from a liquid phase to a vapor phase.
 47. The apparatus of claim41, wherein the apparatus further comprises an exchange materialpositioned within the interface passage at or near the humidifier port,the exchange material configured to collect some or all of the waterintroduced by the humidifier.
 48. The apparatus of claim 47, wherein atleast a portion of the water is introduced into the pressurized air byevaporation as the pressurized air passes through or over the exchangematerial.
 49. The apparatus of claim 41, wherein the vent includes avent valve configurable in: a first valve position wherein the ventvalve is substantially closed so that air flow through the vent is at aminimum; and a second valve position wherein the vent valve issubstantially open so that the air flow through the vent is at amaximum.
 50. The apparatus of claim 41, wherein the humidifier isconfigured such that the introduction of the water into the interfacepassage is periodic.
 51. The apparatus of claim 41, wherein thehumidifier is configured to suspend a flow of the water into theinterface passage during at least a portion of an exhalation phase of abreathing cycle.
 52. An apparatus for providing positive pressurerespiratory therapy to a user, the apparatus comprising: a flowgenerator configured to provide pressurized air at an outlet; a userinterface defining an interface passage in fluid communication with theoutlet of the flow generator, the interface passage defining a vent,wherein the user interface comprises a mask defining a chamber of theinterface passage, the mask configured to attach to the user such thatone or more seals of the mask provides a fluid connection with an airwayof the user, wherein the pressurized air provided by the flow generatoris delivered through the interface passage into the chamber of the maskand through the one or more seals; a humidifier configured to introducewater into the interface passage at a location between the vent and theone or more seals; and a vent valve associated with the vent, the ventvalve configured to be in at least: a closed position during userinhalation; and an open position during user exhalation.
 53. Theapparatus of claim 52, wherein the one or more seals are configured toseal about nares of the user, each of the one or more seals defining anaperture configured to convey the pressurized air to the user's airway.